1. Field of the Invention
The present invention relates to an exercise machine and more particularly, but not by way of limitation, to an exercise machine which utilizes the flow of hydraulic fluid through a restriction to provide opposing force to the operator's applied force.
2. History of the Prior Art
For several years coaches of various athletic sports have realized that body building and muscle exercise is extremely important in developing a athlete so that he can perform in the sport for which he is training. Historically, weight lifting was one of the basic forms of body building exercise used for training athletes. However, in recent years there has been a strong trend toward the use of isometric exercises in place of weight lifting. Positive results have been reported from both types of exercise, but both have definite drawbacks.
While weight lifting provides a relatively smooth work out of the muscles being exercised, the weights have to be often changed to fit the physical needs and size of the user which is very time consuming. Further, a complete weight lifting program requires a substantial outlay of capital, especially when providing weight lifting equipment for use by a physical education class or by a team of athletes.
Further, and more importantly, the weight lifting program has always been accompanied by the danger involved in dropping individual weights during the exercise and the problem of straining a muscle when lifting the weights into position or ending the exercise. In fact, most injuries to weight lifters occur while the weights are being positioned for the desired exercise or setting the weights down after the exercise.
Isometric exercises, on the other hand, do not normally require extensive equipment and are not accompanied by the dangers inherent in weight lifting. However, in performing isometric exercises one applies pressure to an immovable object to exercise particular muscles in one position only which does not allow the muscle to travel through its full range of movement. It has been noted that the typical student of isometric exercises soon loses interest in the exercise since he cannot readily see how much force is being applied and normally he becomes bored with the exercise since there is virtually no movement and hence no sense of accomplishment. Another drawback of the isometric exercise is there is a negligible buildup on the cardiovascular system due to this lack of movement.
Various machines have been developed to provide a moving exercise relying on the passing of hydraulic fluid through various systems in order to regulate the force needed in performing the exercise. A typical machine of this nature is disclosed in the patent to Brentham, U.S. Pat. No. 3,822,599, issued July 9, 1974, for a "EXERCISE DEVICE," wherein a pair of hydraulic cylinders are attached to a movable framework such that the movement of the frame in any direction will require fluid to pass through restriction orifices in order to resist movement of the frame.
Other exercise machines have been developed in order to similate the weight lifting exercise or the isometric exercise and which use, to resist the applied force, various pneumatic flow valves, springs and the like.